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. 2019 Jul 30;8(8):255. doi: 10.3390/plants8080255

Figure 2.

Figure 2

The miR159-GAMYB-like pathway in Arabidopsis. miR159a is the predominant family member, being expressed in seed and throughout plant development at a constantly high level, but it is absent in anthers [8,14,46]. miR159b is expressed at a lower level than miR159a [8,15,46], but its expression pattern appears highly similar to miR159a [14]. miR159c, is weakly expressed and appears mainly confined to anthers [15]. In seeds, miR159 efficacy appears attenuated [48], enabling GAMYB-like gene expression which promotes PCD of the aleurone [41]. In contrast, throughout vegetative development, miR159 efficacy is strong, and MYB33/65 expression is strongly silenced. Only via inhibition of miR159, or mutation of the miR159 binding site within MYB33 or MYB65, will expression occur, which leads to strong deleterious outcomes, such as stunted growth and curled leaves [14,41]. Although the function of the pathway has been suggested to be involved in flowering-time and phase change, the purpose of this pathway in vegetative development is still unclear. In anthers, miR159 activity is low. Here, MYB33 and MYB65 are expressed to promote PCD in the tapetum [43]. MYB97/101/120 expression is required for pollen function [49,50]. Finally, miR159 is required for fertilization [51].