The peach (Prunus persica [L.] Batsch) homeobox gene KNOPE3, which encodes a class 2 knotted-like transcription factor, is regulated during leaf development and triggered by sugars

Abstract

Class 1 KNOTTED1-like transcription factors (KNOX) are known to regulate plant development, whereas information on class 2 KNOX has been limited. The peach KNOPE3 gene was cloned, belonged to a family of few class 2 members and was located at 66 cM in the Prunus spp. G1 linkage-group. The mRNA localization was diversified in leaf, stem, flower and drupe, but recurred in all organ sieves, suggesting a role in sap nutrient transport. During leaf development, the mRNA earliest localized to primordia sieves and subsequently to mesophyll cells of growing leaves. Consistently, its abundance augmented with leaf expansion. The transcription was monitored in leaves responding to darkening, supply and transport block of sugars. It peaked at 4 h after darkness and dropped under prolonged obscurity, showing a similar kinetic to that of sucrose content variation. Feeding leaflets via the transpiration stream caused KNOPE3 up-regulation at 3 h after fructose, glucose and sucrose absorption and at 12 h after sorbitol. In girdling experiments, leaf KNOPE3 was triggered from 6 h onwards along with sucrose and sorbitol raise. Both the phloem-associated expression and sugar-specific gene modulation suggest that KNOPE3 may play a role in sugar translocation during the development of agro-relevant organs such as drupe.

The peach (Prunus persica L. Batsch) genome harbours 10 KNOX genes, which are differentially expressed in stem development, and the class 1 KNOPE1 regulates elongation and lignification during primary growth

“…trunk vigour, branch length, lignin content, and vegetative habitus), which impact on the productivity of forest and fruit arboriculture (Du and Groover, 2010). So far, KNOX genes from Rosaceae fruit trees have only been characterized in apple and peach (Watillon et al, 1997;Testone et al, 2008Testone et al, , 2009. The latter is of economic relevance worldwide and a model for other Prunus spp.…”

“…The KNOPE allelic fragments were amplified from almond 'Texas' (T) and peach 'Earlygold' (E) genotypes using 'Chiripa' primers and analysed for restriction site unequal distribution to create cleaved amplified polymorphic sequence (CAPS) markers ( Table 2). The PCR parameters were the same as described previously (Testone et al, 2009). The digested products (enzyme 5 U, final volume 30 µl) were separated (1.2% agarose).…”

A Strawberry KNOX Gene Regulates Leaf, Flower and Meristem Architecture

“…KNOPE1 transcripts are elevated in leaves infected with Taphrina deformans , leading to leaf curl [26]. Expression patterns of KNOPE3 suggest a role in carbohydrate translocation in addition to organ development [27]. Transgenic plum ( Prunus domestica ) plants overexpressing apple MdKN1 showed reduction in plant height and generated small malformed curly leaves [28].…”

The KNOTTED-like genes of peach (Prunus persica L. Batsch) are differentially expressed during drupe growth and the class 1 KNOPE1 contributes to mesocarp development

“…Tomato class 2 genes also have diversified expression in berry growth and the LeT12 trend recalled that of the orthologue KNOPE3 [14], suggesting that regulation is maintained. KNOPE3 is triggered by monosaccharides [62]; the abundant/constant transcription level in S1/S2 may reflect the responses to glucose and/or fructose, which have typically high contents in S1/S2 [63]. Finally, Arabidopsis class 2 genes are poorly expressed during silique growth except for KNAT7 (Arabidopsis eFP Browser), which exerts control of secondary cell wall biosynthesis [64].…”