Plant melanin is a dark polymerized polyphenolic substance that can by synthesized in seed tissues. Unlike well-defined enzymatic browning reaction leading to melanin synthesis in senescent and damaged plant tissues, melanin formation in intact tissues was not studied properly. Recently, melanin synthesis was demonstrated in chloroplast-derived melanoplasts in pericarp and husk cells of barley seeds. In barley, there are two independent genes, Blp1 and Alm1, affecting respectively the biosynthesis of melanin and chlorophyll in seeds. Even though different genetic systems are responsible for these traits, the localization of these biosynthetic pathways in the same organelle prompted us to conduct an in-depth study of the i:Bwalm1Blp1 line characterized by simultaneous chlorophyll deficiency caused by recessive allele alm1 and melanin accumulation controlled by dominant allele Blp1. This barley line and parental ones—Bowman, i:BwBlp1, and i:Bwalm1, which are characterized by different combinations of pigments chlorophyll and melanin in seeds—were subjected to a comparative cytological analysis. Three markers were analyzed: the presence of visible pigments, chlorophyll, and PsbA protein (a thylakoid membrane marker). Plastids of the barley pericarp and husk showed prominent differences among the lines, with internal structures that are more developed in husk cells. Although chlorophyll deficiency did not prevent melanogenesis in the spike of the hybrid line, a 7-day delay in melanization initiation and a decrease in its magnitude were observed in comparison with the melanin-and-chlorophyll–containing line. Thus, melanin biosynthesis is not related to photosynthetic processes directly but may be dependent on the presence of plastids with well-developed internal membranes.

植物黑色素是一种深色聚合多酚物质，可在种子组织中合成。与明确的酶促褐变反应导致衰老和受损植物组织中的黑色素合成不同，完整组织中的黑色素形成没有得到适当的研究。最近，在大麦种子的果皮和果壳细胞中的叶绿体衍生的黑色素体中证实了黑色素的合成。在大麦中，有两个独立的基因Blp1和Alm1分别影响种子中黑色素和叶绿素的生物合成。尽管不同的遗传系统对这些特征负责，但这些生物合成途径在同一细胞器中的定位促使我们对 i:Bw alm1Blp1进行了深入研究以隐性等位基因alm1引起的叶绿素缺乏和显性等位基因Blp1控制的黑色素积累为特征的系。这个大麦系和亲本 - Bowman、i:Bw Blp1和 i:Bw alm1，其特征在于种子中色素叶绿素和黑色素的不同组合 - 进行了比较细胞学分析。分析了三个标记：可见色素、叶绿素和 PsbA 蛋白（类囊体膜标记）的存在。大麦果皮和外壳的质体在品系之间表现出显着差异，内部结构在外壳细胞中更加发达。尽管叶绿素缺乏并不能阻止杂交品系尖峰中的黑色素生成，但与含有黑色素和叶绿素的品系相比，观察到黑色素化开始延迟了 7 天，并且其幅度有所降低。因此，黑色素生物合成与光合作用过程不直接相关，但可能取决于具有发育良好的内膜的质体的存在。