Abstract Detail

Development and Structure

Montano-Garcia, Jose Antonio [1], Hormaza, Jose Ignacio [2], Lora, Jorge [2], Losada, Juan Manuel [2].

Cell morphology and vascular differentiation in the meristems of diploid, triploid and tetraploid Annona cherimola genotypes.

Unlike in herbaceous crops, the primordial origin of cell size escalation with ploidy is poorly understood in most tree species. Our hypothesis was that the genetic determination of cell size is evidenced at early developmental stages across polyploids of the same species. To test this hypothesis, we used Annona cherimola (Annonaceae), in which diploid, triploid and tetraploid genotypes were available, to compare the cell morphology and vascular differentiation across different ploidies. First, we studied the mobile growth regulator auxin, which has been related to cell division and cell expansion. We used diploid sections of meristems to evaluate the expression of the auxin efflux carrier PIN1 from A. cherimola. Then, histological sections of meristems from the three ploidies served to quantify cell areas in the pith, cortex and the protovasculature.Diploid vegetative meristems displayed canalized expression of AcPIN1 at the domed undifferentiated apical part, but also the lateral leaf primordia, correlated with the areas where the vasculature eventually develops. In the reproductive buds, the expression of AcPIN1 was clearer in the wide domed meristem and in the primordia of gynoecia, and continued during their elongation and differentiation. Cell-wall related pectin epitopes associate to the undifferentiated protovascular cells but, when organs differentiate, their localized accumulation correlates with the sieve tube elements of the phloem. Comparisons across ploidies revealed larger cell sizes in the cortex, the pith, and the protovasculature of the triploids and tetraploids, compared with the diploid cytotypes, but in the reproductive organs, larger cell sizes correlated only with the tetraploids.Our results imply a first approach on the understanding of cell size escalation with ploidy in vegetative and reproductive primordia, and indirectly point to auxin as one of the effectors on organogenesis in both reproductive and vegetative meristems of woody plants.

1 - Institute of Subtropical and Mediterranean Hortofruticulture "La Mayor, Subtropical and Mediterranean Fruticulture, Avenida Dr. Wienberg, sn, Algarrobo-Costa, Malaga, 29750, Spain
2 - Institute of Subtropical and Mediterranean Hortofruticulture La Mayora, Avenida Dr. Wienberg, s/n, Algarrobo-Costa, Malaga, 29750, España

Keywords:
polyploidy
Annona cherimola
Meristem development
PIN1
Phloem Architecture
Vascular.

Presentation Type: Oral Paper
Session: DS1, Development and Structure I
Location: /
Date: Tuesday, July 20th, 2021
Time: 10:00 AM(EDT)
Number: DS1001
Abstract ID:606
Candidate for Awards:Katherine Esau Award