Consequences of root growth kinetics and vascular structure on the distribution of lateral roots

It has been proposed that the acropetal initiation of lateral roots is a built‐in process specified as part of the general process of cell division and differentiation in the parent root tip. Conversely, it is commonly reported that root branching is essentially a variable feature. In the present study, the interlateral distance along the parent root has been investigated using three banana varieties (Musa spp.) grown in two substrates. The pattern of lateral root initiation was obscured by variations of root growth patterns and vascular structure among roots, genotypes and substrates. A framework model is formulated showing the influence of growth pattern and vascular structure on branching density. The model raises a distinction between growth components which should not affect the branching density (i.e. rate of cell division) and which may affect it (i.e. size of mature cells and number of transverse divisions performed by cells executing their trajectory in the meristem). It appears also that lateral root density and root growth rate might be independently modulated by appropriate changes of root growth patterns, in banana and presumably many other taxa.     

Monolignol acylation and lignin structure in some nonwoody plants: a 2D NMR study

Lignins from three nonwoody angiosperms were analyzed by 2D NMR revealing important differences in their molecular structures. The Musatextilis milled-wood-lignin (MWL), with a syringyl-to-guaiacyl (S/G) ratio of 9, was strongly acylated (near 85% of side-chains) at the γ-carbon by both acetates and p-coumarates, as estimated from ¹H-¹³C correlations in C_γ-esterified and C_γ-OH units. The p-coumarate H_3,5-C_3,5 correlation signal was completely displaced by acetylation, and disappeared after alkali treatment, indicating that p-coumaric acid was esterified maintaining its free phenolic group. By contrast, the Cannabissativa MWL (S/G ∼0.8) was free of acylating groups, and the Agavesisalana MWL (S/G ∼4) showed high acylation degree (near 80%) but exclusively with acetates. Extensive C_γ-acylation results in the absence (in M.textilis lignin) or low abundance (4% in A.sisalana lignin) of β-β′ resinol linkages, which require free C_γ-OH to form the double tetrahydrofuran ring. However, minor signals revealed unusual acylated β-β′ structures confirming that acylation is produced at the monolignol level, in agreement with chromatographic identification of γ-acetylated sinapyl alcohol among the plant extractives. In contrast, resinol substructures involved 22% side-chains in the C.sativa MWL. The ratio between β-β′ and β-O-4′ side-chains in these and other MWL varied from 0.32 in C.sativa MWL to 0.02 in M.textilis MWL, and was inversely correlated with the degree of acylation. The opposite was observed for the S/G ratio that was directly correlated with the acylation degree. Monolignol acylation is discussed as a mechanism potentially involved in the control of lignin structure.     

Dimeric phenylphenalenones from Musa acuminata and various Haemodoraceae species. Crystal structure of anigorootin

Three fused octacyclic phenylphenalenone dimers were isolated from Musa acuminata: Anigorootin, which was first isolated from Anigozanthos flavidus and hitherto represented the only compound of that type, the new 4'-hydroxy-anigorootin, and 4',4"-di-hydroxy-anigorootin, which is a revised structure. The crystal structure of anigorootin was determined by X-ray crystallography. 3,3'-Bis-hydroxyanigorufone, a dimer of the conventional type known from Anigozanthos preissii, was also found in Musa acuminata. Phytochemical analysis of several Haemodoraceae species revealed the occurrence of anigorootin, 3,3'-bis-hydroxyanigorufone, and the novel metabolite 3,3'-bis-anigorufone. The occurrence of the same compounds in Musaceae and Haemodoraceae indicates the close chemotaxonomic relationship of both plant families.     

Genome constitution for Musa beccarii (Musaceae) varieties

Borneo is a large island in Southeast Asia. It is divided politically into three parts: the kingdom of Brunei on the north central coast; the Malaysian states of Sarawak and Sabah to the west and east; with Kalimantan of Indonesia making up the larger par…     

壳聚糖提高香蕉幼苗抗冷性的效应

壳聚糖(CS)预处理可降低低温胁迫下香蕉幼苗叶细胞膜脂过氧化水平和膜透性增加的程度以及超氧化物歧化酶(SOD)、过氧化物酶(POD)活性的下降幅度,提高过氧化氢酶(CAT)的活性;0.3%的壳聚糖的保护效果最好.     

Hand position on the bunch and source–sink ratio influence the banana fruit susceptibility to crown rot disease

The postharvest development of crown rot of bananas depends notably on the fruit susceptibility to this disease at harvest. It has been shown that fruit susceptibility to crown rot is variable and it was suggested that this depends on environmental preharvest factors. However, little is known about the preharvest factors influencing this susceptibility. The aim of this work was to evaluate the extent to which fruit filling characteristics during growth and the fruit development stage influence the banana susceptibility to crown rot. This involved evaluating the influence of (a) the fruit position at different levels of the banana bunch (hands) and (b) changing the source–sink ratio (So–Si ratio), on the fruit susceptibility to crown rot. The fruit susceptibility was determined by measuring the internal necrotic surface (INS) after artificial inoculation of Colletotrichum musae. A linear correlation (r = −0.95) was found between the hand position on the bunch and the INS. The So–Si ratio was found to influence the pomological characteristics of the fruits and their susceptibility to crown rot. Fruits of bunches from which six hands were removed (two hands remaining on the bunch) proved to be significantly less susceptible to crown rot (INS = 138.3 mm ²) than those from bunches with eight hands (INS = 237.9 mm ²). The banana susceptibility to crown rot is thus likely to be influenced by the fruit development stage and filling characteristics. The present results highlight the importance of standardising hand sampling on a bunch when testing fruit susceptibility to crown rot. They also show that hand removal in the field has advantages in the context of integrated pest management, making it possible to reduce fruit susceptibility to crown rot while increasing fruit size.     

Occurrence of Ralstonia solanacearum Race 2 Biovar 1 Associated with Moko Disease of Banana (Musa paradisiaca cv. Nipah) in Malaysia

During June 2011 to March 2012, Moko disease symptoms were observed in banana cv. Nipah in two Malaysian states. The primer pairs ISRso19F/ISRso19R were used for defined identification of Ralstonia solanacearum race 2 strain. PCR amplification of all isolates produced a 1900 amplicon and exhibited 93% phylogenetic similarity with reference strain (AF450275). Based on symptoms, biochemical tests, pathogenicity assay, molecular and phylogenetic studies, we concluded that the isolated bacterium was R. solanacearum race 2 biovar 1.     

犬蝠对小果野芭蕉的取食及种子传播

2004年9月到12月,在西双版纳热带植物园沟谷雨林内,通过详细的野外观察和雾网实验以及种子的定时收集方法,对犬蝠(Cynopterussphinx)取食小果野芭蕉(Musaacuminata)的行为及规律进行了研究。发现在夜晚24:00以前,犬蝠取食小果野芭蕉有明显的2个活动高峰,分别发生在20:30和22:30左右,这一结果与雾网采样结果较为一致。在研究期间的雨季(9-10月)和干季(11-12月),犬蝠平均被捕获量为2.2±0.3只/d、1.4±0.3只/d,二者之间没有显著的差异;同时这两个季节收集的种子团数量分别为9.0±1.1个/d和7.2±1.4个/d,也没有显著差异。犬蝠对小果野芭蕉种子的传播受生境影响较为显著,各样地间种子传播的结果大不相同;地点和季节对犬蝠传播种子也不存在交互影响。犬蝠对小果野芭蕉种子的传播距离为50-200m,是小果野芭蕉有效的种子传播者     

Purification and structural analysis of an abundant thaumatin-like protein from ripe banana fruit

 The pulp of ripe bananas (Musa acuminata) contains an abundant thaumatin-like protein (TLP). Characterization of the protein and molecular cloning of the corresponding gene from banana demonstrated that the native protein consists of a single polypeptide chain of 200 amino acid residues. Molecular modelling further revealed that the banana thaumatin-like protein (Ban-TLP) adopts an overall fold similar to that of thaumatin and thaumatin-like PR-5 proteins. Although the banana protein exhibits an electrostatically polarized surface, which is believed to be essential for the antifungal properties of TLPs, it is apparently devoid of antifungal activity towards pathogenic fungi. It exhibits a low but detectable in vitro endo-β-1,3-glucanase (EC 3.2.1.x) activity. As well as being present in fruits, Ban-TLP also occurs in root tips where its accumulation is enhanced by methyl jasmonate treatment of plants. Pulp of plantains (Musa acuminata) also contains a very similar TLP, which is even more abundant than its banana homologue. Our results demonstrate for the first time that fruit-specific (abundant) TLPs are not confined to dicots but occur also in fruits of monocot species. The possible role of the apparent widespread accumulation of fruit-specific TLPs is discussed. Received: 7 January 2000 / Accepted: 26 April 2000     

油菜素内酯提高香蕉幼苗抗冷性的效应

冷胁迫条件下的香蕉幼苗分别经不同浓度的BR处理后,相对于对照来说,在一定的处理浓度范围内,可以明显的降低电解质外渗率,提高低温胁迫下香蕉幼苗叶片中SOD的活性,一定程度上提高了低温胁迫下香蕉幼苗叶片中可溶性蛋白的含量,减缓叶片中MDA的含量变化,可溶性糖含量明显的提高,减少叶片萎蔫面积和死亡率,同时,明显的减缓了叶片中叶绿素降解的速度。这些代谢产物的变化,对提高香蕉幼苗冷胁迫期间的抵抗能力起着非常关键和重要的作用。保护效果最好的浓度是：0.9 mg·L^-1。