Nie Lixiao, Song Shaokun, Yin Qi, Zhao Tingcheng, Liu Hongyan, He Aibin, Wang Weiqin
Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, College of Tropical Crops, Hainan University, Haikou, China.
College of Agronomy, Hunan Agricultural University, Changsha, China.
Rice (N Y). 2022 Mar 27;15(1):19. doi: 10.1186/s12284-022-00567-3.
Chilling stress is the major abiotic stress that severely limited the seedling establishment of direct-seeded rice in temperate and sub-tropical rice production regions. While seed priming is an efficient pre-sowing seed treatment in enhancing crop establishment under abiotic stress. Our previous research has identified two seed priming treatments, selenium priming (Se) and salicylic priming (SA) that effectively improved the seed germination and seedling growth of rice under chilling stress. To further explore how seed priming enhance the starch degradation of rice seeds under chilling stress, the present study evaluated the effects of Se and SA priming on germination and seedling growth, α-amylase activity, total soluble sugar content, hormone content and associated gene relative expression under chilling stress. The results showed that both Se and SA priming significantly increased the seed germination and seedling growth attributes, and enhanced the starch degradation ability by increasing α-amylase activity and total soluble sugar content under chilling stress. Meanwhile, seed priming increased the transcription level of OsRamy1A, OsRamy3B that regulated by GA, and increased the transcription level of OsRamy3E that regulated by sugar signals. Furthermore, seed priming significantly improved the GA contents in rice seeds by up-regulating the expression of OsGA3ox1 and OsGA20ox1, and decreased the ABA content and the expression of OsNCED1, indicating that the improved starch degradation ability in primed rice seeds under chilling stress might be attributed to the increased GA and decreased ABA levels in primed rice seeds, which induced the expression of GA-mediated α-amylase. However, studies to explore how seed priming mediate hormonal metabolism and the expression of OsRamy3E are desperately needed.
低温胁迫是主要的非生物胁迫，严重限制了温带和亚热带水稻产区直播水稻的秧苗建立。种子引发是一种有效的播前种子处理方法，可增强非生物胁迫下作物的生长。我们之前的研究确定了两种种子引发处理方法，即硒引发（Se）和水杨酸引发（SA），它们能有效提高低温胁迫下水稻种子的萌发和幼苗生长。为了进一步探究种子引发如何增强低温胁迫下水稻种子的淀粉降解，本研究评估了Se和SA引发对低温胁迫下种子萌发、幼苗生长、α-淀粉酶活性、总可溶性糖含量、激素含量及相关基因相对表达的影响。结果表明，Se和SA引发均显著提高了种子萌发和幼苗生长指标，并通过提高低温胁迫下的α-淀粉酶活性和总可溶性糖含量增强了淀粉降解能力。同时，种子引发提高了受GA调控的OsRamy1A、OsRamy3B的转录水平，以及受糖信号调控的OsRamy3E的转录水平。此外，种子引发通过上调OsGA3ox1和OsGA20ox1的表达显著提高了水稻种子中的GA含量，并降低了ABA含量和OsNCED1的表达，这表明低温胁迫下引发水稻种子淀粉降解能力的提高可能归因于引发种子中GA含量增加和ABA含量降低，从而诱导了GA介导的α-淀粉酶的表达。然而，迫切需要开展研究来探究种子引发如何介导激素代谢以及OsRamy3E的表达。
