Weller J L, Schreuder M E, Smith H, Koornneef M, Kendrick R E
Laboratory of Plant Physiology, Graduate School of Experimental Plant Sciences, Wageningen University, Arboretumlaan 4, NL6703 BD Wageningen, The Netherlands.
Plant J. 2000 Nov;24(3):345-56. doi: 10.1046/j.1365-313x.2000.00879.x.
The role of phytochrome B2 (phyB2) in the control of photomorphogenesis in tomato (Solanum lycopersicum L.) has been investigated using recently isolated mutants carrying lesions in the PHYB2 gene. The physiological interactions of phytochrome A (phyA), phytochrome B1 (phyB1) and phyB2 have also been explored, using an isogenic series of all possible mutant combinations and several different phenotypic characteristics. The loss of phyB2 had a negligible effect on the development of white-light-grown wild-type or phyA-deficient plants, but substantially enhanced the elongated pale phenotype of the phyB1 mutant. This redundancy was also seen in the control of de-etiolation under continuous red light (R), where the loss of phyB2 had no detectable effect in the presence of phyB1. Under continuous R, phyA action was largely independent of phyB1 and phyB2 in terms of the control of hypocotyl elongation, but antagonized the effects of phyB1 in the control of anthocyanin synthesis, indicating that photoreceptors may interact differently to control different traits. Irradiance response curves for anthocyanin synthesis revealed that phyB1 and phyB2 together mediate all the detectable response to high-irradiance R, and, surprisingly, that the phyA-dependent low-irradiance component is also strongly reduced in the phyB1 phyB2 double mutant. This is not associated with a reduction in phyA protein content or responsiveness to continuous far-red light (FR), suggesting that phyB1 and phyB2 specifically influence phyA activity under low-irradiance R. Finally, the phyA phyB1 phyB2 triple mutant showed strong residual responsiveness to supplementary daytime FR, indicating that at least one of the two remaining phytochromes plays a significant role in tomato photomorphogenesis.
利用最近分离出的在PHYB2基因中携带损伤的突变体，研究了光敏色素B2（phyB2）在番茄（Solanum lycopersicum L.）光形态建成控制中的作用。还利用所有可能的突变体组合的同基因系列和几种不同的表型特征，探索了光敏色素A（phyA）、光敏色素B1（phyB1）和phyB2的生理相互作用。phyB2的缺失对白光培养的野生型或phyA缺陷型植物的发育影响可忽略不计，但显著增强了phyB1突变体细长的淡色表型。在连续红光（R）下的去黄化控制中也观察到了这种冗余现象，在phyB1存在的情况下，phyB2的缺失没有可检测到的影响。在连续R下，就下胚轴伸长的控制而言，phyA的作用在很大程度上独立于phyB1和phyB2，但在花青素合成的控制中拮抗phyB1的作用，这表明光感受器可能以不同方式相互作用以控制不同性状。花青素合成的辐照度响应曲线表明，phyB1和phyB2共同介导了对高辐照度R的所有可检测到的响应，令人惊讶的是，在phyB1 phyB2双突变体中，依赖phyA的低辐照度成分也大大降低。这与phyA蛋白含量的降低或对连续远红光（FR）的反应性无关，表明phyB1和phyB2在低辐照度R下特异性影响phyA活性。最后，phyA phyB1 phyB2三突变体对补充的白天FR表现出强烈的残余反应性，表明剩余的两种光敏色素中至少有一种在番茄光形态建成中起重要作用。
