Genetic analysis of post-flowering drought tolerance and components of grain development in Sorghum bicolor (L.) Moench

Drought is a serious agronomic problem and the single greatest factor contributing to crop yield loss in the world today. This problem may be alleviated by developing crops that are well adapted to dry-land environments. Sorghum (Sorghum bicolor (L.) Moench) is one of the most drought-tolerant grain crops and is an excellent crop model for evaluating mechanisms of drought tolerance. In this study, a set of 98 recombinant inbred (RI) sorghum lines was developed from a cross between two genotypes with contrasting drought reactions, TX7078 (pre-flowering-tolerant, post-flowering susceptible) and B35 (pre-flowering susceptible, post-flowering-tolerant). The RI population was characterized under drought and non-drought conditions for the inheritance of traits associated with post-flowering drought tolerance and for potentially related components of grain development. Quantitative trait loci (QTL) analysis identified 13 regions of the genome associated with one or more measures of post-flowering drought tolerance. Two QTL were identified with major effects on yield and 'staygreen under post-flowering drought. These loci were also associated with yield under fully irrigated conditions suggesting that these tolerance loci have pleiotropic effects on yield under non-drought conditions. Loci associated with rate and/or duration of grain development were also identified. QTL analysis indicated many loci that were associated with both rate and duration of grain development. High rate and short duration of grain development were generally associated with larger seed size, but only two of these loci were associated with differences in stability of performance under drought.     

A salivary secretory protein from Riptortus pedestris facilitates pest infestation and soybean staygreen syndrome

The bean bug (Riptortus pedestris), one of the most important pests of soybean, causes staygreen syndrome, delaying plant maturation and affecting pod development, resulting in severe crop yield loss. However, little is known about the underlying mechanism of this pest. In this study, we found that a salivary secretory protein, Rp614, induced cell death in nonhost Nicotiana benthamiana leaves. NbSGT1 and NbNDR1 are involved in Rp614-induced cell death. Tissue specificity analysis showed that Rp614 is mainly present in salivary glands and is highly induced during pest feeding. RNA interference experiments showed that staygreen syndrome caused by R. pedestris was significantly attenuated when Rp614 was silenced. Together, our results indicate that Rp614 plays an essential role in R. pedestris infestation and provide a promising RNA interference target for pest control.