早实核桃脂肪积累与酶活性动态及其相关性

以绿岭和绿早2个早实核桃品种为试材,对开花50 d后不同发育时期核仁的脂肪含量与3种相关的酶活性动态进行研究,分析不同发育时期影响核桃脂肪含量的关键酶.结果表明: 2个品种的核仁脂肪积累动态一致,核仁在开花后50 d开始固化,花后60～90 d核仁脂肪含量迅速增加,花后90～120 d增长幅度变缓,花后120～130 d脂肪含量停止增长.利用Logistic模型对核桃脂肪积累进程进行拟合(P<0.01),绿岭脂肪积累盛期为开花后57.8～85.8 d,绿早为开花后67.4～92.1 d.乙酰辅酶A羧化酶(ACCase)、6-磷酸葡萄糖脱氢酶(G6PDH)和丙酮酸激酶(PK)活性均在花后50～100 d呈上升趋势,随后酶活性呈下降趋势.核仁脂肪含量与ACCase活性呈显著正相关;脂肪积累速率与PK活性呈显著正相关;不同发育时期脂肪含量与酶活性的相关性不同.花后50～100 d是核桃核仁脂肪合成旺盛的时期,此时加强田间栽培管理可以提高脂肪含量.在核桃脂肪合成前期G6PDH是影响脂肪含量的主要酶,PK活性影响丙酮酸形成,从而间接影响脂肪的合成.ACCase活性影响了最终的脂肪含量,并在脂肪合成的各个时期均起到重要的调节作用,是影响核桃脂肪合成的关键酶.

Dynamics of and relationship between fat accumulation and enzyme activities of precocious walnut

Two precocious walnut varieties, Lvling and Lvzao were used as materials in this study, the kernel fat contents and 3 related enzyme activities in different development periods after flowe-ring 50 days were analyzed. The key enzymes affecting walnut fat in different periods were illumina-ted. The results showed that the kernel fat accumulation trends of the two varieties were basically the same. The kernel began to solidify 50 days after flowering, and the increase in kernel fat content was rapid 60-90 days after flowering, slowed down 90-120 days after flowering, and stopped 120-130 days after flowering. The Logistic model was used to fit the fat accumulation (P<0.01). Fat content rapid accumulation period was 57.8-85.8 days after flowering for Lvling, and 67.4-92.1 days after flowering for Lvzao. The activities of acetyl-CoA carboxylase (ACCase), 6-phosphate dextrose dehydrogenase (G6PDH) and pyruvate kinase (PK) increased from 50 to 100 days after flowering, and then the activities of enzymes began to decrease. The kernel fat content was positively correlated with the activity of ACCase. The kernel fat accumulation rate was positively correlated with PK enzyme activity. The correlation between fat content and enzyme activity was different at different development stages. The 50-100 days after flowering was the exuberant period of walnut kernel fat synthesis, and at this time the fat content could be improved by strengthening the field cultivation management measures. At the early stage of the walnut fat synthesis, G6PDH was the major enzyme to affect fat content, and PK activity influenced the formation of pyruvic acid, so as to indirectly affect the synthesis of fat. ACCase activity affected the final fat content and ACCase played an important regulating role in every period of fat synthesis. It was speculated that ACCase might be a key enzyme to affect the fat synthesis of walnut kernel.