Placido Dante F, Dong Niu, Dong Chen, Cruz Von Mark V, Dierig David A, Cahoon Rebecca E, Kang Byung-Guk, Huynh Trinh, Whalen Maureen, Ponciano Grisel, McMahan Colleen
Bioproducts Research Unit, Western Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Albany, CA, United States.
Guayule Research Farm, Section Manager Agricultural Operations, Bridgestone Americas, Inc., Eloy, AZ, United States.
Front Plant Sci. 2019 Jun 26;10:760. doi: 10.3389/fpls.2019.00760. eCollection 2019.
We report functional genomics studies of a CYP74 rubber particle protein from , commonly called guayule. Previously identified as an allene oxide synthase (AOS), this CYP74 constitutes the most abundant protein found in guayule rubber particles. Transgenic guayule lines with gene expression down-regulated by RNAi () exhibited strong phenotypes that included agricultural traits conducive to enhancing rubber yield. lines had higher leaf and stem biomass, thicker stembark tissues, increased stem branching and improved net photosynthetic rate. Importantly, the rubber content was significantly increased in lines compared to the wild-type (WT), vector control and overexpressing () lines, when grown in controlled environments both in tissue-culture media and in greenhouse/growth chambers. Rubber particles from plants consistently had less AOS particle-associated protein, and lower activity (for conversion of 13-HPOT to allene oxide). Yet plants with downregulated showed higher rubber transferase enzyme activity. The increase in biomass in lines was associated with not only increases in the rate of photosynthesis and non-photochemical quenching (NPQ), in the cold, but also in the content of the phytohormone SA, along with a decrease in JA, GAs, and ABA. The increase in biosynthetic activity and rubber content could further result from the negative regulation of expression by high levels of salicylic acid in lines and when introduced exogenously. It is apparent that AOS in guayule plays a pivotal role in rubber production and plant growth.
我们报道了对一种来自银胶菊（通常称为银胶菊）的细胞色素P450 74橡胶颗粒蛋白的功能基因组学研究。该细胞色素P450 74先前被鉴定为丙二烯氧化物合酶（AOS），是在银胶菊橡胶颗粒中发现的最丰富的蛋白质。通过RNA干扰（RNAi）下调基因表达的转基因银胶菊品系表现出强烈的表型，包括有利于提高橡胶产量的农艺性状。RNAi品系具有更高的叶和茎生物量、更厚的茎皮组织、增加的茎分枝和提高的净光合速率。重要的是，与野生型（WT）、载体对照和过表达（OE）品系相比，当在组织培养基以及温室/生长室的可控环境中生长时，RNAi品系中的橡胶含量显著增加。来自RNAi植物的橡胶颗粒始终具有较少的与AOS颗粒相关的蛋白质和较低的活性（用于将13-HPOT转化为丙二烯氧化物）。然而，基因下调的植物显示出更高的橡胶转移酶活性。RNAi品系生物量的增加不仅与光合作用速率和非光化学猝灭（NPQ）在低温下的增加有关，还与植物激素水杨酸含量的增加以及茉莉酸、赤霉素和脱落酸含量的降低有关。生物合成活性和橡胶含量的增加可能进一步源于RNAi品系中高水平水杨酸对基因表达的负调控以及外源引入水杨酸时的情况。显然，银胶菊中的AOS在橡胶生产和植物生长中起关键作用。
